With the tremendous increase in the number of home personal computers (PCs), as well as business PCs, currently in use, there has been a corresponding increase in computer software or programs for use with such PCs. For example, specialized application programs have been developed for everything from presenting elaborate spread sheets and desktop publishing to sophisticated computer games. In general, such application programs (or other confidential or secretive software) are sold to the end user either directly by the individual or company which developed the program, or through an established distribution network which may include mail order and/or retail sales outlets. In many cases, such programs (i.e. software) are stored on a standard magnetic disc within a supporting disc cartridge to facilitate loading of the software onto a PC hard drive for performing the desired tasks.
Control of such software, particularly confidential and/or valuable software distributed on discs, has become a problem due to the ease with which a program stored on such a disc may be duplicated. Although, in theory, copyright laws protect software developers from unauthorized copying of such programs, it is impractical, if not impossible, for software developers to fully enforce their copyrights, particularly against companies or individuals making a relatively small number of copies of such software. For example, a small company may purchase a single copy of original software from the developer and may then produce four or five unauthorized copies of the purchased software for separate use on computers or other PCs at different locations within the company. Likewise, a group of individuals may combine their money to purchase a single original of the software for a particular computer game, for example, and then make a number of unauthorized copies for separate use of the software by each of the individuals within the group on their own computers. In either event, it is difficult for the developer or owner of the original software to enforce the copyright.
Various methods have been developed to prevent unauthorized copying of software. One such method involves requiring the purchaser of the software to enter into a license agreement which permits use of the software only upon a single designated computer and prohibits the purchaser from making unauthorized copies. This form of protection is difficult and expensive to enforce, particularly when dealing with a large member of small companies and individuals.
A second form of protection requires utilizing a secret code or password which must be obtained from the software supplier and entered when using the software. While this form of protection has merit, it still does not preclude unauthorized use or copying on a relatively small scale since the code or password may be obtained by one person from the software supplier and then easily given to others within a small company or a group.
A third form of protection involves placing restrictions within the computer program itself which completely preclude copying or permit only a single copy of the program or software to be made. One problem with this type of protection used as a sale means of protection is that such restrictions within the computer program which completely preclude copying prevent the purchaser from copying the software onto his/her PC hard drive or even making a single backup copy, as permitted by law. Additionally, restrictions in programs which permit only a single copy of the program to be made are problematic in that specialized programs have been developed to circumvent or override this type of protection. Such program restrictions are susceptible to being broken or avoided so that multiple copies may then be made.
U.S. Pat. No. 4,325,089 discloses a system for safeguarding magnetically recorded data in which sensors are provided for generating destruct signals responsive to attempts to gain unauthorized access to the data (software). A control circuit responds to the destruct signals for energizing an electromagnet simultaneously with rotation of the turntable so that the disc is carried through the electromagnetic field created by the magnet for erasing the data. In such a manner, the software stored on the disc is destroyed or erased in response to unauthorized attempts to gain access to the software (e.g. any attempt to break into the housing or even to bodily carry the housing away). Unfortunately, the system of the '089 patent is undesirably bulky and does not provide for limiting the number of copies which may be made of the software to a predetermined number. Additionally, this system may result in the software being unintentionally erased or destroyed before it is ever used by the rightful user.
U.S. Pat. No. 4,975,898 discloses a method and apparatus for preventing copying of an optical disc. In the system of the '898 patent, a standard program and an erasing program are non-rewritably recorded optically on a predetermined region of a disc. The erasing program attempts to erase the non-rewritable standard software portion upon use, this attempt having no effect on the original disc, but will, in fact, erase the standard software portion on a disc which is copied. Thus, if the software and the basic data for executing the program are copied without authorization, the copied disc is prevented from being used because if it is used, the copied standard software will be erased by the copied erasing program. Unfortunately, the system of the '898 patent does not provide a way in which to limit the number of copies made of the software stored on the original disc. Additionally, it is not beyond the realm of possibilities that the erasing program on the original disc may be disabled, circumvented, or rendered useless, in which case, there is no limit upon the number of copies which may be made of the original software, authorized or unauthorized.
U.S. Pat. No. 4,660,116 discloses a video tape cassette with an internal tape erasing system designed to erase data from the tape as it is wound onto the takeup reel, thereby providing for one time viewing only of the prerecorded material. Unfortunately, the system of the '116 patent is designed for use with a video tape cassette and may not be used in conjunction with discs, which are more prevalent in current computer systems. Also, unintentional erasure of data may easily occur with such a desire.
U.S. Pat. No. 5,057,947 discloses a system for limiting the number of copies which may be made of material from a digital audio tape. Again, many tape erasing/destroying systems are not applicable to magnetic disc technology. Furthermore, inhibiting copying by way of software or hardware is not as efficient as simply erasing or destroying the material from the original disc after copying.
U.S. Pat. No. 4,849,836 discloses a system for preventing copying of software from computer discs, the system including a key sequence in a copy protection section of a program which is deliberately rendered ambiguous by repeatedly recording a word containing that sequence while gradually shifting the phase of the transition of a portion of the sequence until the sequence becomes a different sequence. This gradual phase shift cannot be reproduced if the disc is copied onto a standard PC so that the inconsistency on successive readouts will not be present in use via a copied disc. The program is designed so that it cannot run unless inconsistencies are detected in successive readouts in the copy protection section of the program. Again, such software based copy prevention techniques both 1) prevent copying a single time from one disc to another; and 2) are not as efficient as simply erasing the software after a predetermined number of acceptable copies have been made.
U.S. Pat. No. 4,866,769 discloses a copy protection system for PC software distributed on discs which provides a unique ID stored in a RAM of a PC in which software on a disc is to be used. This ID is accessible to the user of the computer. Prior to each use of the program, the software on the disc uses the PC and the source IDs and checkword to verify that the software is being used on the same PC on which it was installed. Unfortunately, authorized users often must switch PCs or use a backup copy or the like on another PC.
U.S. Pat. No. 5,199,066 discloses a method and apparatus for protecting software in which the use of software is enabled only when a predetermined intermediate code and a predetermined software code are identical. Again, this is a software based method of protection which is both expensive to produce and maintain, and is susceptible to being overcome.
FIG. 1 is a top elevational view of prior art magnetic disc cartridge 1 encasing disc 3. FIG. 2 is a front elevational view of cartridge 1 as viewed from the front or shutter edge of the cartridge. Cartridge 1 includes a housing or case made from synthetic resin which includes lower case or half 4 and upper case or half 5. Cartridge 1 rotatably houses and encases magnetic disc 3. Shutter 7 is slidably provided along the front edge side of cartridge 1 so as to open and close head insert opening 9 upon insertion and removal of cartridge 1 into and from a conventional computer (i.e. PC) respectively.
Head insert opening 9 defined within the cartridge body is opened by movement of shutter 7 when the cartridge is inserted into a computer due to the presence of rectangular aperture 11 defined in the body of the shutter, apertures 9 and 11 being aligned so as to open head insert opening 9 when the shutter is forced to the right as shown in FIG. 1 so that the head within the computer may access disc 3. Spring 13 including ends 15 and 17 is provided within the cartridge so as to engage shutter 7 thereby biasing the shutter toward the closed position when the cartridge is outside of the computer as shown in FIG. 1. At the center of cartridge 1, center opening 19 is provided so that metallic hub 21 provided at the center of magnetic disc 3 is exposed to the outside of the cartridge. Hub 21 is engagable with a turntable within the PC so that disc 3 may be rotated. For a further description of the magnetic disc cartridge shown in FIGS. 1-2, see U.S. Pat. No. 5,121,380 the disclosure of which is incorporated herein by reference.
In view of the above, it is apparent that there exists a need in the art for a more efficient and simpler apparatus/method for limiting the number of copies which may be made of software originally stored in a magnetic disc cartridge. The need exists for a system which completely erases or destroys the software after a predetermined number of copies have been made, thereby absolutely preventing further copying from the original magnetic disc. Furthermore, there exists a need in the art to render the copied version of the software noncopyable in the future (e.g. via a software code inserted into or copied onto the copied disc with the software).